Ending a two-day trip intended to cement ties with Ukraine's new Moscow-friendly leadership, Medvedev said the two nations' energy companies should work out ways to bolster their cooperation.

"We must think about the future on a pragmatic basis and without enforcing any scenarios," he said at a Russian-Ukrainian business forum.

Russian Prime Minister Vladimir Putin recently proposed merging the assets of Russia's state gas monopoly, Gazprom, and Ukraine's Naftogaz company. The proposal has drawn sharp criticism from the Ukrainian opposition, which sees it as an attempt by Moscow to wrest control over the country's most prized industrial asset - a sprawling network of gas pipelines carrying 80 percent of Russian natural gas exports to Europe.

Ukraine's President Viktor Yanukovych - already under fire from the opposition for signing a deal to extend the Russian navy's stay in Ukraine - said the proposed merger should leave each side with equal stakes in the new company. Russia wants a controlling stake.

No merger agreement was signed during Medvedev's trip, but Gazprom chief Alexei Miller said Monday that negotiations were happening and that Gazprom would modernize Ukraine's gas transportation system if the merger took place.

Putin's deputy in charge of energy, Igor Sechin, said Tuesday that Gazprom and Naftogaz may create a joint venture as a first step toward closer integration, the ITAR-Tass news agency reported. He added that Gazprom would like to win access to Ukraine's domestic energy market.

Under Ukraine's former president, Viktor Yushchenko, disputes with Moscow resulted in Russia twice shutting down its supply of natural gas to Europe, prompting the EU to seek alternative routes that did not go through Ukraine. Russia also has pursued other export pipelines bypassing Ukraine.

Ukraine's Fuel and Energy Minister Yuriy Boyko on Tuesday lamented the lack of certainty regarding the future Russian gas transit shipments in view of the prospective North Stream and South Stream pipelines.

Medvedev said the new pipeline projects would go ahead, but that the two nations could develop energy cooperation in other ways.

Yanukovych has pushed for more cooperation in the aircraft and shipbuilding industries, in which Ukraine excelled during the Soviet times. Russia and Ukraine plan to jointly resume production of the Soviet-designed An-124, the world's biggest heavylift transport aircraft, and to manufacture several other planes designed by the Kiev-based Antonov bureau.

Yanukovych, elected in February, has sought to boost ties with Russia in contrast with his Western-leaning predecessor, Yushchenko, who irked Moscow by seeking membership in NATO and the EU. Last month, Yanukovych signed a deal allowing Russia to extend its lease of the Black Sea Port of Sevastopol for 25 years after the current agreement expires in 2017. Russia rewarded Ukraine with deep discounts for natural gas.

Medvedev said Russia would welcome Ukraine's joining the Moscow-dominated security pact uniting several ex-Soviet nations, but also said the Kremlin was happy for Ukraine to maintain its current neutral status.